Physics MCQs

Question #1081

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Diffraction demonstrates light's:

A. EM nature

B. Particle nature

C. Dual nature

D. Wave nature

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Correct Answer: Option D

Explanation:
Diffraction (bending around obstacles) is wave phenomenon explained by Huygens' principle. Particle model predicts straight-line propagation. Memory aid: 'Diffraction/interference ⇒ wave nature; photoelectric ⇒ particle nature'. Wave-particle duality frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1082

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Sound resonance used in:

A. Neither

B. Tuning forks

C. Musical instruments

D. Both

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Correct Answer: Option D

Explanation:
Resonance amplifies sound at natural frequency: instruments (guitar body), tuning forks (frequency standard). Memory tip: 'Resonance: musical instruments (amplify), tuning forks (calibration), avoid in bridges'. Wave application frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1083

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Pendulum period independent of:

A. Small amplitude

B. Length

C. Gravity

D. Bob mass

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Correct Answer: Option D

Explanation:
T = 2π√(l/g): depends on l and g, independent of mass (gravitational and inertial mass cancel). Memory aid: 'Pendulum: T ∝ √(l/g); independent of mass for small angles'. Oscillations concept frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1084

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Polarization used in:

A. LCD displays

B. Glare-reducing sunglasses

C. Neither

D. Both

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Correct Answer: Option D

Explanation:
Polarized sunglasses block reflected glare (horizontal polarization). LCDs use liquid crystals to rotate polarization for pixel control. Memory tip: 'Polarization: sunglasses (glare reduction), LCDs (display technology)'. Optics application frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1085

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Gravity work for horizontal motion:

A. Negative

B. Speed dependent

C. Positive

D. Zero

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Correct Answer: Option D

Explanation:
Gravity acts vertically; horizontal displacement ⇒ angle = 90° ⇒ W = Fd cos90° = 0. No work for perpendicular force-displacement. Memory aid: 'Work = Fd cosθ; θ=90° ⇒ W=0'. Mechanics concept frequently tested to correct misconception that force always does work.

This question belongs to: Science Physics

Question #1086

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The dimensional formula of Planck's constant is same as that of

A. Angular momentum

B. Linear momentum

C. Force

D. Energy

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Correct Answer: Option A

Explanation:
Planck's constant h = E/ν. Dimensions: [ML²T⁻²]/[T⁻¹] = [ML²T⁻¹]. Angular momentum = mvr = [ML²T⁻¹]. Linear momentum [MLT⁻¹], force [MLT⁻²], energy [ML²T⁻²]. So angular momentum matches. This is a frequently asked SSC question.

This question belongs to: Science Physics

Question #1087

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If the random error in measurement of radius of a sphere is 2%, the error in volume is

A. 8%

B. 2%

C. 6%

D. 4%

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Correct Answer: Option C

Explanation:
Volume V = (4/3)πr³. Fractional error ΔV/V = 3 Δr/r. Percentage error = 3 × 2% = 6%. Important for error analysis in competitive exams.

This question belongs to: Science Physics

Question #1088

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Which of the following has the least count of 0.001 cm?

A. Metre scale

B. Measuring tape

C. Screw gauge

D. Vernier calliper

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Correct Answer: Option C

Explanation:
Screw gauge typically has least count 0.001 cm (0.01 mm). Vernier calliper least count 0.01 cm. Metre scale 0.1 cm. So screw gauge most precise.

This question belongs to: Science Physics

Question #1089

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1 joule is equal to how many ergs?

A. 10⁵

B. 10⁶

C. 10⁸

D. 10⁷

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Correct Answer: Option D

Explanation:
1 J = 1 kg m²/s². In CGS, 1 kg = 10³ g, 1 m = 10² cm => 1 J = (10³ g) × (10² cm)² / s² = 10⁷ g cm²/s² = 10⁷ erg. Key conversion.

This question belongs to: Science Physics

Question #1090

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The number of significant figures in 0.02040 is

A. 2

B. 3

C. 5

D. 4

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Correct Answer: Option D

Explanation:
Leading zeros not significant. '2040' – trailing zero after decimal is significant. So digits 2,0,4,0 are significant = 4. Rule: zeros between non-zero and trailing zeros after decimal count.

This question belongs to: Science Physics

Question #1091

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If X = a²b³/c², and percentage errors in a, b, c are 2% each, the maximum percentage error in X is

A. 12%

B. 8%

C. 14%

D. 10%

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Correct Answer: Option C

Explanation:
ΔX/X = 2(Δa/a) + 3(Δb/b) + 2(Δc/c) = 2×2% + 3×2% + 2×2% = 4% + 6% + 4% = 14%. Always add absolute relative errors.

This question belongs to: Science Physics

Question #1092

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A car moving with speed 54 km/h is stopped in 5 s. The distance covered before stop is

A. 54 m

B. 75 m

C. 37.5 m

D. 27 m

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Correct Answer: Option C

Explanation:
54 km/h = 15 m/s. u=15, v=0, t=5. a = (0-15)/5 = -3 m/s². s = ut+½at² = 15×5 + ½×(-3)×25 = 75 - 37.5 = 37.5 m. Or s = (u+v)/2 × t = 7.5×5 = 37.5 m.

This question belongs to: Science Physics

Question #1093

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A body falls freely from rest. The ratio of distances covered in 1st, 2nd, and 3rd seconds is

A. 1:3:5

B. 1:4:9

C. 1:1:1

D. 1:2:3

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Correct Answer: Option A

Explanation:
s_nth = u + (g/2)(2n-1). u=0 => s ∝ (2n-1). So 1, 3, 5. Classic kinematic ratio.

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Question #1094

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A projectile is fired with velocity u at angle 45° with horizontal. Its time of flight is (g = 10 m/s²)

A. u/5√2

B. √2 u/5

C. √2 u/10

D. u/5

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Correct Answer: Option C

Explanation:
T = 2u sinθ/g = 2u sin45°/10 = 2u(1/√2)/10 = √2 u/10. SSC often tests projectile basics.

This question belongs to: Science Physics

Question #1095

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The maximum height attained by a projectile is H when angle of projection is 30°. For angle 45° and same u, height will be

A. 2H/√3

B. 3H/2

C. 2H

D. H/√3

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Correct Answer: Option C

Explanation:
H ∝ sin²θ. H₁ ∝ sin²30 = 1/4. H₂ ∝ sin²45 = 1/2. Ratio H₂/H₁ = (1/2)/(1/4) = 2. So H₂ = 2H.

This question belongs to: Science Physics

Question #1096

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In uniform circular motion, which of the following is constant?

A. Centripetal acceleration

B. Kinetic energy

C. Velocity

D. Linear momentum

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Correct Answer: Option B

Explanation:
Speed constant, so kinetic energy (½mv²) constant. Velocity, acceleration, momentum change direction.

This question belongs to: Science Physics

Question #1097

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A body of mass 2 kg moves with velocity 3 m/s. It is subjected to a force of 4 N in direction of motion for 2 s. Final velocity is

A. 5 m/s

B. 8 m/s

C. 6 m/s

D. 7 m/s

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Correct Answer: Option D

Explanation:
a = F/m = 4/2 = 2 m/s². v = u + at = 3 + 2×2 = 7 m/s. Impulse = Δp = 8 N s, initial momentum 6, final 14 => v=7 m/s.

This question belongs to: Science Physics

Question #1098

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A man of mass 60 kg stands on a weighing machine in a lift accelerating upward at 2 m/s². Reading in kg wt (g=10) is

A. 72 kg

B. 48 kg

C. 60 kg

D. 80 kg

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Correct Answer: Option A

Explanation:
Apparent weight = m(g+a) = 60×12 = 720 N. In kg wt, 720/10 = 72 kg. So machine shows 72 kg. Downward acceleration would show less.

This question belongs to: Science Physics

Question #1099

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Two balls of masses m and 2m are dropped from a height h. Neglecting air resistance, which hits the ground with greater momentum?

A. m

B. Depends on height

C. Both same

D. 2m

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Correct Answer: Option D

Explanation:
Both reach same velocity v = √(2gh). Momentum = mass × v, so larger mass has greater momentum. KE different, but momentum differs.

This question belongs to: Science Physics

Question #1100

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A bullet of mass 20 g fired from a gun of mass 5 kg with speed 500 m/s. Recoil velocity of gun is

A. 2 m/s

B. 0.5 m/s

C. 1 m/s

D. 2.5 m/s

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Correct Answer: Option A

Explanation:
Momentum conservation: 0 = 0.02×500 + 5×v => v = -10/5 = -2 m/s (magnitude 2 m/s).

This question belongs to: Science Physics

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